Hello all,

I am in the market for a G37S sedan, one with a 6 speed manual transmission. After scouting much of the internet with 370z/g37 5th gear grinds, I am inconclusive on a few areas.

I test drove a 2012 G37S sedan and experienced this 5th gear grind, 2 out of the 3 times I put the car into 5th. At first I apologized to the sales guy, till I realized after the second time it wasn't me . I asked him why and he said its because the car has been sitting for a while...which led me to google the issue. I am not new to manual cars, my last car was stick and its not user error here.

Its under warranty with only 40k miles. But what bothers me is that its really inconclusive if the problem has been fixed. All I read about is the trans being replaced numerous times...

So owners, was/is there a updated transmission that fixed this issue? I do not want to dump $30k+ into a car only to have a serious powertrain issue, that will resurface eventually (and more importantly), after warranty.

Thanks in advance.

 

There is no fix nor update to my knowledge. If you have it under warranty, get it replaced for free. If it is out of warranty, walk away. I had this issue as well, it was not "because the car has been sitting".

 

Thanks for your input. I love the car. To give you some background, I came from a 2006 Acura tsx. The gearbox was so smooth, and with the added mods (short shifter, shifter cable bushings (No cables on a RWD car), and a weighted countersunk ****), made the shift feel crisp, precise, and smooth.

Flash forward to the G..its a blend of sportiness like the tsx, but has way more tech features, and unlike the tsx, actually has power and is a proper sports sedan layout (FR). LOL.

You say you had this issue...does that mean you got it replaced, or got rid of the car?

I want the car, but I just want it to come again on a replacement transmission...20-30k miles later after its out of warranty.

Is there conclusive evidence that the redline MT-90 MTF fixes this?

Sorry for all these questions, I am trying to build a firm case to buy or walk away from the car. I'm trying my hardest to build a case for it at this point, lol.

Thanks everyone.

 

Any gearing grinding is usually a result of synchro wear. MT90 is usually too thick for most areas. MT85 is the preferred fluid.

 

Thanks for your input. So MT85 is the way to go.

I understand its the synchros, but to your knowledge, has it been revised in later year models? I know 09 MY's had the most issues, but the one I am looking at is a 2012..

Does MT-85 fix or bandage this?

 

^^I can't say with certainty. Maybe some longer time owners can chime in on whether there were any internal revisions in the MT with later model years.

I mainly switched to the MT85 early on to try to cure an annoying whine in warmer weather. The sound lost some amplitude but is still present. When it's 60F or cooler outside, the noise is barely audible.

 

OP dont purchase that vehicle unless that tranny gets knocked out 1st. I had issues with my 6 speed manual tranny...couldn't engage 5th gear w/o massive grinding so I took it to the dealership, mind u I have tons of mods, and they still replaced it under warranty. Theres quite a bit of bad manual Z & G trannys out there...so dont spend that 30k+ just to have a bad one.

 

I think the ability to replace out of warranty depends on your dealer and your service advisor. Luckily my problem occurred at 40K. So I got it covered (full tranny replacement) under warranty at no charge. I did however also notice a slight buzzing on the front passenger side window motor. This is a known issue (power window motors burning out) so I told my service advisor that I knew it was a problem and that I'd like it replaced. He told me that he was not able to replace it until it failed completely but that he would note it down so that one day if it did fail I would still get it replaced for free since I first brought the issue up while I was still under warranty. Now I know a transmission is a lot more than a power window motor but if you are able to secure some kind of agreement like this with your service advisor then I probably would feel ok getting the car. With that being said, make sure you get this agreement in writing lol.

 

Thanks I will definitely make it a situation where I will buy the car only if its replaced.

I will definitely do that. Thanks.

How has your replacement transmission held up? How many miles since you replaced it at 40k?

Do you skip gears, and/or do you shift slowly?

One thing I used to do on the tsx was skip gears..not something crazy like 2nd to 6th, but 2nd to 4th and 3rd to 5th or 4th to 6th. Nothing that put too much wear on the synchros.

I also did shift hard (no, not powershift lol). I pretty much would abuse the motor and gearbox and it was super reliable for the 4 years I owned the car.

Ive read that on the Z's and G's you have to shift slowly...which is crazy considering its a sports coupe/sedan.

 

So far I'm at 49K so not even 10K on the new tranny yet. It's felt good and smooth so far. I do skip gears but only when coasting or going downhill and only from 3rd to 5th, and never under load. I shift quickly/hard occasionally but I don't think it has impacted the synchros or gears or else the "5th gear grind" issue would be the "2nd gear grind issue". I mean who "power shifts" from 4th to 5th?

 

Your sales guy either doesn't know what he is talking about or he's full of it. Unless you fumbled the shift, that's a bad synchro.

I read about the weak 5th and 6th synchros before buying my 6MT. Skip shifting seems to be part of the problem and I do it all the time, but I hesitate slightly and shift slow. That has an effect similar to double-clutching by allowing the engine RPMs to drop and more closely match for the upshift.

 

Thats good to know and that makes sense (on skip shifting under no load).

And yeah, no real necessity to shift fast/hard going into 5th. It still irks me that you are limited to your shifting style on a manual car. Thought it was all about giving the driver control lol. But the rest of the car makes up for it.

Yeah I really thought it was me, that I might have clutched out too soon...but mind you I wasn't on that throttle that much and shifting at 3000 rpms...it was more of me trying to modulate the clutch pedal and feel the engagement point...which is really hard with that stupid spring. Already looked into the DIY to remove that. So I was certain I didnt mess up by the second time.

Funny thing, the 3rd time I put it into 5th I made sure to shift slow, and pretend the car had a gated shifter. It didnt crunch that time.

I guess it all comes down to putting as little wear on the synchros. Be it rev matching (even on an upshift ). The car I am looking at was a lease, so I doubt the lessee gave a ****.

Time to ask for a replacement transmission on the sales order.

 

I bought my 2011 Sedan 6MT about a year ago and have put 15k miles on it since.

During the winter, on cold mornings, the trans would grind going into 5th, no matter how carefully I shifted. And it wasn't clutch engagement either.

It would only do it when the car was cold.

As the weather is warming up it was grinding less, but still every morning.

I called the local dealer and they told me to bring it in.

The next day they called and said that when they drained the MT fluid, that it had metal chunks in it.

So, the trans, slave cylinder, and throwout bearing were replaced at no cost to me. They told me the clutch disc looked great and that there were no signs of abuse by me (I knew that) or by the previous owner.

The new trans shifts much smoother.

Here's hoping for no more of these issues.

 

Yeah it's definitely not "user error" for the most part. I would be sitting at a stoplight with the car stopped. With the clutch pressed in all the way, I would go into any gear no problem but the minute I tried to shift into 5th.. CRRUUUUNCH. Definitely talk to you service advisor, it's a known issue. Guaranteed.

 

Hey my car just started doing this with 27k! It is under warranty and they are probably going to replace the transmission since I dropped it off yesterday so I can't tell you if it will resolve it but everything else is smooth just 5th which is a really weird gear to have synchro issues with